Preventive interventions targeting parents of young children are among the most important investments society can make, especially among families living in low-income communities. However, research indicates that only 30-50% of low-income families participate in preventive interventions at levels sufficient to improve parent-child behavioral outcomes. While there is data indicating that competing demands, stressful living conditions, and limited resources pose significant barriers to participation, we know little about how parents'intrinsic and extrinsic motivations to participate enable them to overcome these barriers. The goals of this study are to better understand (1) what motivates low-income parents of young children to enroll in preventive interventions centered on their children, (2) how those motivations relate to participation (attendance and active engagement) in the intervention, and (3) the degree to which those motivations predict improvements in parent-child outcomes. This proposed study is part of a larger NIH-funded study to evaluate the cost- effectiveness of financial incentives on increasing participation rates in a preventive parent training (PT) program called the Chicago Parent Program. The proposed study will advance knowledge on (1) how parent motivations affect participation and improvements in parent-child outcomes and (2) the extent to which financial incentives affect parent participation and parenting outcomes when those incentives are identified as the primary motivator for enrollment, a key question as the nation focuses greater attention on financial incentives for motivating a wide range of health behavior changes. This study is a vital first step toward achieving this applicant's long-term career goal of developing a theory of participation for prevention programs relevant to vulnerable families with young children. The specific aims of this study are to examine the extent to which parents'motivations to enroll in the parent training (PT) program (1) are related to participation (attendance and engagement) in PT sessions;(2) are related to theoretically relevant family characteristics (parent race/ethnicity, parent age, parent income, parent education, child gender, child age);(3) moderate relationships between family characteristics and participation in PT;(4) predict improvements in parent-child outcomes (parenting self-efficacy, parenting behavior, child behavior problems);and (5) differentially affect participation and parent-child outcomes when financial incentives are identified as the primary motivator for enrollment. These aims are consistent with the NIH-wide priority to advance knowledge in prevention and health behavior change. The study will use a prospective longitudinal design, following 174 low-income parents of young children (96% ethnic minority) from enrollment in PT to 1 year post-intervention. A model based on self- determination theory (SDT), a macro theory of human motivation, will be used to guide the study, and structural equation modeling will be used to test the theoretical model. PUBLIC HEALTH RELEVANCE: This study seeks to increase understanding of how parents'motivations to enroll in preventive parent training programs relate to (1) participation (attendance and engagement) in parent training sessions and (2) parent-child outcomes. Although parent training has been shown to improve parent and child outcomes, participation rates in these programs are typically very low, especially among vulnerable populations. A better understanding of parents'motivations and the impact of these motivations can inform future recruitment and messaging strategies for preventive parent training programs as well as prevention programs overall.